Cleaning Device

ABSTRACT

A device for cleaning a continuously revolving clothing in a machine producing and/or processing a paper, cardboard, tissue or other fiber web, includes at least one cleaning nozzle generating at least one fluid cleaning jet directed towards the clothing and a channel discharging fluid and dirt from the clothing in a discharge direction. The discharge channel has a first portion with a receptacle opening at the beginning of the discharge channel and a cleaning opening facing the clothing forming a cleaning zone. The nozzle causes the jet to impact the clothing in the cleaning zone. The receptacle opening is oriented opposite a clothing running direction and the nozzle provides the jet with a velocity component transverse to the running direction striking the clothing in an angular range 20°&lt;B&lt;80°, particularly 30°&lt;B&lt;70° relative to a clothing plane seen in the clothing running direction.

The invention relates to a device for cleaning a continuously revolvingclothing in a paper machine for producing and/or processing a paper,cardboard, or tissue web or another fibrous web, said device comprisingat least one cleaning nozzle which from a fluid generates at least onecleaning jet that is directed onto the clothing, and a discharge ductfor discharging the fluid and the dirt that is released from theclothing by the cleaning jet in a discharging direction, wherein thedischarge duct has a first portion having a receptacle opening at thebeginning of the discharge duct, wherein the first portion of thedischarge duct has a cleaning opening that points toward the revolvingclothing and forms a cleaning zone, and the at least one cleaning nozzleis disposed in such a manner that the at least one cleaning jet impactsthe clothing in the region of the cleaning zone.

The invention also relates to a method for cleaning a continuouslyrevolving clothing in a paper machine for producing and/or processing apaper, cardboard, or tissue web or another fibrous web.

Different clothings are used in the various sections of a paper machine.Said clothings serve for transporting the fibrous web from one sectionto another, on the one hand, and said clothings are tuned to thetechnological procedures in the respective sections, on the other hand.The forming screens in the forming section facilitate the uniformde-watering of the fibrous suspension; the press felts in the presssection absorb the water that has been squeezed out; and said clothingsin the drying section support the fibrous web and transport the watervapor away from the fibrous web.

In all cases, the clothings are contaminated with fines, fillers, andimpurities from the fibrous web. In order for the properties of theclothings to remain consistent for as long as possible and to becompromised to the least possible extent, said clothings need to becleaned. This applies not only to the air-permeable and water-permeableclothings mentioned, but also to water-impermeable belts which are usedin the press section, for example.

A known cleaning device is known from publication WO 2005/113890 A1. Itis proposed therein for a cleaning nozzle for cleaning a transportationbelt to be used such that the cleaning jet always impacts thetransportation belt counter to the running direction of thetransportation belt. The cleaning nozzle herein in the running directionof the transportation belt is disposed behind or at the end of thecleaning device. This arrangement has the disadvantage that the mixtureof cleaning medium and dirt always has to be suctioned counter to therunning direction of the transportation belt. This requires acorrespondingly high input of energy. Also, there is a noticeabletendency towards contamination of the surroundings by the formation offog which can also be charged with dirt particles, in particular whenthe suction output in the suction duct is held at too low a level, orwhen the velocity of the cleaning jet is increased.

The invention is therefore based on the object of avoiding thedisadvantages of the known cleaning devices, of improving the cleaningeffect, and of proposing a simple and cost-effective device.

The object is achieved by the features of claim 1.

A device for cleaning a continuously revolving clothing in a papermachine for producing and/or processing a paper, cardboard, or tissueweb or another fibrous web is proposed said device comprising at leastone cleaning nozzle which from a fluid generates at least one cleaningjet that is directed onto the clothing, and a discharge duct fordischarging the fluid and the dirt that is released from the clothing bythe cleaning jet in a discharging direction. The discharge duct has afirst portion having a receptacle opening at the beginning of thedischarge duct, wherein the first portion of the discharge duct has acleaning opening that points toward the revolving clothing and forms acleaning zone, and that the at least one cleaning nozzle is disposed insuch a manner that the at least one cleaning jet impacts the clothing inthe region of the cleaning zone. It is provided according to theinvention that the receptacle opening points counter to the runningdirection of the revolving clothing, and in that the at least onecleaning nozzle is disposed such that the at least one cleaning jet hasa velocity component in the transverse direction, that is to saytransversely to the running direction of the clothing, and, when viewedin the running direction of the clothing, the cleaning jet (4) inrelation to the clothing plane impacts the clothing at an angular rangeof 20°<B<80°, in particular at an angular range of 30°<B<70°.

The clothing plane is meant to be that plane which is defined by thecontinuously revolving clothing, preferably in the region of the deviceand preferably in the region of the cleaning zone. The cleaning zone isto be understood to be that space which is delimited by the dischargeduct, preferably by the first portion of the latter, and the clothingthat revolves directly opposite said discharge duct, thus the clothingplane.

When mention is made of the receptacle opening pointing counter to therunning direction of the revolving clothing, this is to be understood asfollows: the extension of the longitudinal central axis of the firstportion of the discharge duct together with the running direction of theclothing, preferably when viewed in the region of the cleaning zone,forms the smallest angle seen, which is less than 90° and preferably issmaller than or equal to 45°. The feature according to the invention ofthe receptacle opening pointing counter to the running direction of therevolving clothing refers to the operation of the device according tothe intended use. The latter is present when the device is disposed inon the on paper machine in relation to the clothing, and when the atleast one cleaning jet impacts the clothing.

The angle B lies in the plane that is defined by the transversedirection and a perpendicular to the clothing plane.

The cleaning jet thus impacts the region of the cleaning zone. The termregion preferably also includes that region that is close to theperiphery and adjacent to the cleaning opening, as long as the fluid andthe released dirt can be reliably discharged in the discharge duct. Inthis case, the cleaning zone is larger than the cleaning opening.

The at least one cleaning nozzle is preferably disposed so as to bestationary in relation to the device.

According to the invention, the receptacle opening is disposed counterto the running direction of the clothing to be cleaned. On accountthereof, a driving effect is created by the entrained air barrier layer.The kinetic energy of the air barrier layer entrained by the clothingherein is utilized for facilitating the discharge of the fluid and thedirt that is released from the clothing by the cleaning jet into thedischarge duct. The discharging direction and the running direction ofthe clothing thus point in substantially the same direction. Bothdirections can also diverge by up to 30° from one another without theaction of the driving effect being substantially compromised. Thecontamination of the surroundings is likewise reduced by thisarrangement, since the impact point of the cleaning jet on the clothinglies entirely within the first portion of the discharge duct.Additionally, the cleaning effect is improved by the orientation of thecleaning jet according to the invention. In the case of clothings, inparticular in the case of drying screens, the cleaning jet by virtue ofthe weaving structures can penetrate further into the woven dryingscreen fabric and clean a larger portion of the open volume.

The device can be embodied so as to be separate from the paper machine.This means that said device is capable of being (can be) disposed in theregion of the continuously revolving clothing of the paper machine, andthe at least one cleaning jet is directable onto the clothing.

The device for cleaning is preferably disposed on the external side ofthe revolving clothing, that is to say on that side of the clothing thatfaces the fibrous web, and can be coupled to a traversing installationthat extends in the transverse direction, that is to say in thedirection that is transverse to the running direction of the clothing.

In one practical embodiment, the at least one cleaning nozzle isdisposed such that the at least one cleaning jet, when viewed in a planethat is parallel with the clothing plane, in relation to the transversedirection impacts the clothing at an angular range of −45°<A<45°. Whenviewed in the running direction 9, the cleaning jet impacts the clothingplane at an angle B, on the one hand, and said cleaning jet ispreferably oriented so as to be transverse to the running direction ofthe clothing, on the other hand. In one practical case, good resultswere able to be achieved at an angular range of −20°<A<20°. Very goodresults for many clothings could be achieved a complete orientation inthe transverse direction, that is to say at A=0°. The angle A thus liesin the plane that is defined by the transverse direction and the runningdirection of the clothing.

In one further practical design embodiment, the first portion of thedischarge duct in the region of the cleaning opening is assigned asliding shoe, wherein the sliding shoe surrounds the cleaning opening,that is to say that the sliding shoe does not obscure the cleaningopening. The first portion of the discharge duct herein is connected tothe sliding shoe, for example by screw-fitting or welding. The slidingshoe during the cleaning operation of the device slides on the clothing,or has a minor spacing of less than 3 mm, preferably less than 2 mmtherefrom. On account of the direct contact with the clothing, or onaccount of the minor spacing from the clothing, the suction space of thefirst portion of the discharge duct is sealed in relation to thesurroundings such that flows of air or fog that arise from the firstportion of the discharge duct are prevented or at least minimized.Contamination of the device and of the surroundings is reduced onaccount thereof. The fluid that is reflected by the clothing and thedirt that is released therefrom are completely discharged.

According to one refinement it is possible for the sliding face of theside of the sliding shoe that faces the clothing to be provided withgrooves wherein the grooves in the running direction of the clothing canextend from the beginning of the sliding shoe up to the cleaningopening.

It is furthermore also conceivable for the first portion of thedischarge duct in the region of the cleaning opening to be embodied suchthat said first portion, without the use of a sliding shoe, bearsdirectly on the clothing. To this end, a sliding face is configured onthe first portion of the discharge duct.

In one further potential embodiment, the periphery that surrounds thecleaning opening of the first portion of the discharge duct, or of thesliding shoe, that forms the cleaning zone is provided with a slant. Theslant herein is embodied such that the face of the cleaning openingincreases in size toward the interior space of the discharge duct. Thisshape has proven advantageous in terms of discharging coarsecontaminants that adhere to the clothing. On account of this geometry,the dirt is scraped from the clothing and discharged.

In one advantageous variant of embodiment, the flow cross section of thefirst portion of the discharge duct increases in the dischargingdirection. The receptacle opening thus has the smallest cross section ofthe first portion of the discharge duct. On account thereof, the risk ofleakage of fluid and contaminants as a result of air turbulence iscounteracted. However, it is also conceivable for the flow cross sectionto decrease or remain consistent.

In order for the adherence of dirt to the internal wall of the firstportion of the discharge duct, in particular of the entire dischargeduct, to be avoided, the flow cross section at least of the firstportion of the discharge duct possesses exclusively rounded corners.This is of significance in particular when the discharge duct, inparticular the first portion of the discharge duct, possesses anon-circular flow cross section, for example a rectangular flow crosssection. In one particularly advantageous embodiment, the flow crosssection at least of the first portion of the discharge duct is embodiedso as to be tubular, and is preferably made from a tube.

In order for the contamination of the first portion of the dischargeduct, in particular of the entire discharge duct, to be avoided orreduced, the internal wall and/or the external wall can have non-stickproperties and to this end be coated with non-stick materials or becomposed of such materials. Such non-stick materials can compriseTeflon, for example.

In one practical embodiment, the face of the cleaning opening in thedischarging direction is inclined in relation to the centerline of thein particular tubular discharge duct; the face of the cleaning openingin the discharging direction preferably runs so as to diverge from thecenterline of the discharge duct. A particularly advantageous shape ofthe cleaning opening which can also be produced in a simple manner iscreated on account of this embodiment. If the first portion of thedischarge duct is made from a tube, the cleaning opening is thusimparted a parabolic shape when the tube is not cut parallel with thecenterline. If a rectangular tube is used and the cleaning opening islikewise generated by a cut that is not parallel with the centerline, arectangular shape is thus created.

The cleaning opening advantageously begins at the receptacle opening atthe beginning of the discharge duct. The air barrier layer that isentrained by the clothing can thus make its way unimpeded into the firstportion of the discharge duct and into the open cleaning zone.

In one practical embodiment, the cleaning opening has a shape which inparticular steadily tapers in the discharging direction. Said cleaningopening has a parabolic shape, for example. Since the cleaning openingruns parallel with the clothing plane and is preferably in contact withthe latter or is positioned at a minor spacing therefrom, contaminantsthat adhere to the clothing can thus be gently scraped off by theperiphery of the cleaning opening. Vibrations are thus also not createdsuch as can be the case with a rectangular shape of the cleaningopening, since the air barrier layer and the contaminants hereinabruptly meet at the end edge of the opening that extends across thewidth of the cleaning opening.

The at least one cleaning nozzle in the first portion of the dischargeduct is expediently disposed in the lateral wall of the discharge ductand/or in the sliding shoe. Said cleaning nozzle is preferably disposedsuch that it does not project beyond the wall of the discharge duct intothe interior space of the discharge duct. Deposits are avoided onaccount thereof. If the cleaning nozzle is disposed in the sliding shoe,the former can also be disposed such that the cleaning jet in theadjacent peripheral region of the cleaning zone impacts the clothingsuch that the fluid and the contaminants can still be reliablydischarged in the discharge duct. In one practical embodiment, at leasttwo mutually opposite cleaning nozzles which are preferably offset inthe running direction of the clothing are provided.

The fluid of the cleaning jet can comprise water and/or air and/orsteam.

The first portion of the discharge duct can have a preferably adjustableaperture for delimiting the face of the receptacle opening.

As has already been addressed, the cleaning opening is preferablydisposed so as to be substantially parallel with the clothing.

The discharge duct is expediently suctioned.

In one practical embodiment, the first portion of the discharge duct isfollowed by a further portion, wherein the further portion has a bend,and the discharging direction directly after the bend is directed awayfrom the clothing.

According to one preferred practical refinement, propulsion jet nozzlesare provided in the region of the bend of the further portion. Thepropulsion jet nozzles are preferably disposed such that the latter actin the discharging direction, preferably directly after the bend. Thisarrangement possesses a simple and cost-effective construction andenables energy to be incorporated across the entire cross section of thedischarge duct directly after the bend. The propulsion jet nozzles areexpediently disposed in a nozzle block which is connected to thedischarge duct.

In one further variant of embodiment, additionally to the at least onecleaning nozzle, at least one blow down nozzle that is operated by agaseous medium such as air, for example, can be disposed in the firstportion of the discharge duct. On account thereof, the clothing afterhaving been cleaned can be relieved of fluid of the at least onecleaning jet. The arrangement and the orientation of the blow downnozzle can be the same as with the cleaning nozzles.

The first and the further portion of the discharge duct are preferablymade from tubes. The nozzle block can likewise have a cylindrical shapewhich preferably has the same diameter as the discharge duct. A compact,cost-effective construction mode that has a low tendency towardcontamination is enabled on account thereof. This construction mode isalso easy to clean.

The object is also achieved by a method for cleaning a continuouslyrevolving clothing in a paper machine for producing and/or processing apaper, cardboard, or tissue web or another fibrous web. The methodcomprises the following steps:

-   -   generating from a fluid at least one cleaning jet that is        directed onto the clothing;    -   providing a discharge duct;    -   discharging the fluid and the dirt that is released from the        clothing by the cleaning jet in a discharging direction;    -   configuring a receptacle opening in a first portion of the        discharge duct;    -   configuring within the first portion of the discharge duct a        cleaning opening that points toward the revolving clothing and        forms a cleaning zone; and    -   orienting the at least one cleaning jet toward the cleaning        zone.

It is provided according to the invention that the receptacle opening isoriented counter to the running direction of the revolving clothing, andthat the at least one cleaning nozzle is disposed such that the at leastone cleaning jet, when viewed in the running direction of the clothing,in relation to the clothing plane impacts the clothing at an angularrange of 20°<B<80°.

The present invention also relates to a paper machine mentioned at theoutset, comprising at least one continuously revolving clothing and atleast one device according to the invention for cleaning said clothing.

The device furthermore also relates to the use of a device according tothe invention in the paper machine mentioned above.

Further features and advantages of the invention are derived from thedescription hereunder of preferred exemplary embodiments with referenceto the drawing in which:

FIG. 1 shows an exemplary embodiment of a device according to theinvention in a schematic and perspective illustration;

FIG. 2 shows a side view of the embodiment as per FIG. 1;

FIG. 2b shows a front view of the embodiment as per FIG. 1;

FIG. 3 shows a perspective illustration of a fragment of the embodimentas per FIG. 1;

FIG. 4 shows a front view of the embodiment as per FIG. 1 in a schematicillustration;

FIG. 5 shows a further perspective illustration of a fragment of theembodiment as per FIG. 1;

FIG. 6 shows a schematic illustration of the lower side of the slidingshoe; and

FIG. 7 shows a schematic illustration of a fragment of the embodiment asper FIG. 1, in the sectional plan view.

Equivalent elements in the figures have been identified by identicalreference signs.

A device 1 according to the invention is shown in a schematic andperspective illustration in FIG. 1. The clothing 2 that is shown infragments is a drying screen for drying a fibrous web in a dryingsection of a paper machine, said drying screen revolving in the runningdirection 9. The device 1 is connected to a traversing installation (notillustrated) and during the cleaning operation is reciprocatedcontinuously or in intervals in the transverse direction 9.1. The entirerevolving clothing 2 that in the region of the device 1 defines aclothing plane 2.1 can thus be cleaned. The device 1 comprises adischarge duct 5 which has a first portion 5.1. The latter is made froma tube and therefore has no rectangular or acute-angled corners in theinterior. The tendency toward contamination is thus minor. The firstportion 5.1 has a receptacle opening 6. The device 1 in relation to thedrying screen 2 is disposed such that the receptacle opening 6 pointscounter to the running direction 9. The air barrier layers that areentrained by the drying screen thus pass the receptacle opening 6 at avelocity that is almost identical to the velocity of the drying screen.The first portion 5.1 of the discharge duct 5 has a cleaning opening 12that points toward the drying screen 2 and forms a cleaning zone 13. Ineach case one cleaning nozzle 3, 3.1 is disposed laterally so as to bestationary in the wall of the first portion 5.1 of the discharge duct 5,said cleaning nozzles 3, 3.1 being disposed so as to be mutually offsetin the running direction 9. In order to counteract any risk ofcontamination, the cleaning nozzles 3, 3.1 do not protrude into thedischarge duct 5.1. The cleaning nozzles 3, 3.1 each deliver a cleaningjet 4 of cleaning fluid, in this example of water. The cleaning jets 4meet on the drying screen 2 in the cleaning zone 13 and releasecontaminants. The latter, together with the cleaning fluid, aredischarged in the discharging direction 8 from the cleaning zone 13 inthe direction of the running direction 9 of the clothing 2, that is tosay of the drying screen 2 in this example. The flow cross section ofthe first portion 5.1 of the discharge duct 5, beginning at thereceptacle opening 6, increases in the discharging direction 8. Saidflow cross section at the end possesses a circular cross section whichis adjoined by a further portion of the discharge duct 5. This furtherportion is tubular and has a bend such that the discharging direction 8in this portion changes such that the fluid and the releasedcontaminants are guided away from the drying screen 2 in a dischargingdirection 8.1 after the bend for further treatment outside the papermachine. A nozzle block having propulsion jet nozzles 15 is disposed inthe region of the bend such that the propulsion jet nozzles 15 areoriented in the direction of the discharging direction 8.1 after thebend, and act in this direction. The first portion 5.1 of the dischargeduct 5 in the region of the cleaning opening 12 is assigned a slidingshoe 10, wherein the sliding shoe 10 surrounds the cleaning opening 12,that is to say that the sliding shoe 10 does not obscure the cleaningopening 12. The first portion 5.1 of the discharge duct 5 herein isconnected to the sliding shoe 10 by welding or screw-fitting, forexample. The sliding shoe 10 during the cleaning operation of the device1 slides on the clothing, or has a minor spacing of less than 3 mm,preferably of less than 2 mm therefrom. On account of the direct contactwith the clothing, or on account of the minor spacing from the clothing,the suction space of the first portion of the discharge duct is sealedin relation to the surroundings such that flows of air and fog thatarise from the first portion are prevented or at least minimized.Contamination of the device 1 and the surroundings is reduced on accountthereof. The sliding shoe 10 at the beginning in the running direction 9of the clothing 2 has runners which run so as to be bent away from thedrying screen, so as to guarantee a smooth run-up of the drying screen2. At the same time, damage to the drying screen in the case ofmalfunctions and of an unstable running of the clothing is avoided onaccount thereof. The fluid that is reflected by the drying screen 2 andthe released dirt are thus completely discharged. The discharge duct 5is connected to a suction installation (not illustrated). Reliabledischarging of the fluid and of the released contaminants is guaranteedon account thereof.

A side view of the embodiment as per FIG. 1 is schematically illustratedin FIG. 2. It can be seen that the flow cross section of the firstportion 5.1 of the discharge duct 5, beginning at the receptacle opening6, increases in the discharging direction 8. At the end, said flow crosssection possesses a circular cross section which is adjoined by afurther portion of the discharge duct 5. This further portion is tubularand has a bend such that the discharging direction 8 in this portionchanges so that the fluid and the released contaminants from the dryingscreen 2 are guided away in a discharging direction 8.1 after the bendto further treatment outside the paper machine. A nozzle block 14 havingpropulsion jet nozzles 15 is disposed in the region of the bend suchthat the propulsion jet nozzles 15 are oriented in the direction of thedischarging direction 8.1 after the bend, and act in this direction. Itcan also be readily seen that the entire cross section of the dischargeduct 5 after the bend is impinged by the propulsion jet nozzles 15 onaccount of this arrangement. This results in a highly effectivepropulsion effect. The supply line 16 for the propulsion jet nozzles 15is also integrated in the nozzle block 14. It can also be seen from thisillustration that the cleaning opening 12 runs in a diverging inclinedmanner in relation to the discharging direction 8 which correspondssubstantially to the profile of the centerline 5.2 of the dischargeduct.

FIG. 2b shows a front view of the embodiment as per FIG. 1. Beyond thedescription of the device 1 to date, the exit of a propulsion jet nozzle15 into the discharge duct 5 in the region of the bend can be seen here.

FIG. 3 shows a perspective simplified illustration of a fragment of theembodiment as per FIG. 1. The sliding shoe 10 is embodied withoutrunners which however could likewise be applied in this example. Theshape of the cleaning opening 12 can be identified in this illustration.Said cleaning opening 12 has a shape which steadily tapers in thedischarging direction 8. Said cleaning opening 12 here has a parabolicshape. Since the cleaning opening runs so as to be parallel with theclothing plane and is in contact with the latter or is positioned at aminor spacing therefrom, contaminants that adhere to the drying screen 2can thus be gently scraped off by the periphery 12.1 of the cleaningopening. The periphery 12 which surrounds the cleaning opening 12 of thefirst portion 5.1 of the discharge duct 5, or of the sliding shoe 10,that forms the cleaning zone 13 is provided with a slant such that asharp edge is formed. The slant herein is embodied such that the face ofthe cleaning opening 12 increases in size toward the interior space ofthe discharge duct 5.1. This shape has proven advantageous in terms ofdischarging coarse contaminants that adhere to the clothing. On accountof this geometry, the dirt is scraped from the clothing and discharged.Vibrations are thus also not created such as can be the case with arectangular shape of the cleaning opening, since the air barrier layerand the contaminants herein abruptly meet at the end edge of the openingthat extends across the width of the cleaning opening 12. The cleaningopening 12 begins at the receptacle opening 6 at the beginning of thedischarge duct. The air barrier layer that is entrained by the dryingscreen 2 can thus makes its way unimpeded into the first portion 5.1 ofthe discharge duct 5 and into the open cleaning zone 13.

FIG. 4 shows a front view of the embodiment as per FIG. 1 in a schematicillustration. In this variant of embodiment, the cleaning nozzles 3, 3.1are arranged in the sliding shoe 10. As a result of the impulse of thecleaning jet 4, the drying screen 2 is somewhat raised from the slidingshoe 10. The cleaning jets 4 impact the drying screen 2 somewhat outsidethe cleaning opening 12. The cleaning zone 13 in this case is largerthan the cleaning opening 12. The cleaning zone 13 can thus also includethat region that is close to the periphery and is adjacent to thecleaning opening 12, as long as the fluid and the released dirt can bereliably discharged in the discharge duct 5. The reflected cleaning jets4 are illustrated in dashed lines and are entirely received by the firstportion 5.1 of the discharge duct 5 and discharged in a dischargingdirection 8. The cleaning jets 4 possess a velocity component in thetransverse direction and are inclined in relation to the clothing 2. Byvirtue of the woven structure, a very good cleaning effect is achievedon account of the velocity component in the transverse direction inparticular in the cleaning of drying screens. The angle B in relation tothe clothing plane 2.1 in this example is 40°. The angle A in relationto the transverse direction can be in the range between −45° and +45°,as can be seen from FIG. 7. The cleaning jet 4 in this example isoriented exactly in the transverse direction, that is to say that saidcleaning jet 4 has no velocity component in the running direction 9. Theangle A is thus 0°.

FIG. 5 shows a further perspective illustration of a fragment of theembodiment as per FIG. 1. The first portion 5.1 of the discharge duct 5in this example possesses an aperture 7 which reduces the cross sectionof the first portion 5.1 of the discharge duct 5 at the beginning. Thereceptacle opening 6 is thus smaller than the cross section of the firstportion 5.1 of the discharge duct 5 at the beginning. The aperture 7 canbe fixedly connected to the discharge duct 5. However, it is alsopossible for said aperture 7 to be embodied so as to be adjustable. Theflow conditions can be optimized on account thereof.

A schematic illustration of the lower side of the sliding shoe 10 isshown in FIG. 6. Said lower side in the region of the cleaning opening12 has grooves 11 which can run so as to be rectilinear or curved, as isillustrated in an exemplary manner on the right and the left. Thegrooves 11 extend in the running direction of the clothing, from thebeginning of the sliding shoe 10 up to the cleaning opening 12. Onaccount of this arrangement, the grooves 11 are perfused by the airbarrier layer that is entrained by the drying screen 2, and thus makesits way into the first portion 5.1 of the discharge duct 5. This has theeffect of sealing and rinsing the periphery of the cleaning opening 12.Overall, this leads to a lower tendency towards contamination of thedevice 1 on the external side as well as on the internal side.

FIG. 7 shows a schematic illustration of a fragment of the embodiment asper FIG. 1 in the plan view and in sectional form in the region of thefirst portion 5.1 of the discharge duct 5. In each case one cleaningnozzle 3, 3.1 is disposed in the lateral wall of the first portion 5.1.The cleaning nozzles 3, 3.1 do not protrude into the interior space ofthe first portion 5.1. The cleaning jets 4 generated impact the dryingscreen 2 within the cleaning opening 12. The impact points areillustrated as circles. The cleaning jets 3, 3.1 in this example havedifferent directions in relation to the transverse direction 9.1 and,when viewed in a plane that is parallel with the clothing plane 2.1, areestablished by the respective angle A between the cleaning jet 3, 3.1and a line that runs parallel with the transverse direction 9.1. Theangle A can be between −45° and +45°, wherein the cleaning jet 4 in thecase of positive angles possesses a velocity component in the runningdirection, and the cleaning jet 4 in the case of negative anglespossesses a velocity component counter to the running direction 9. Inone preferred embodiment, this can be the angle A=0°. The direction ofthe cleaning jets 3, 3.1 in relation to the clothing is thus establishedby a solid angle which is defined by the angle A and by the angle Bshown in FIG. 4.

LIST OF REFERENCE SIGNS

1 Device

2 Clothing

2.1 Clothing plane

3 Cleaning nozzle

3.1 Cleaning nozzle

4 Cleaning jet

5 Discharge duct

5.1 First portion of the discharge duct

5.2 Centerline of the discharge duct

6 Receptacle opening

7 Aperture

8 Discharging direction

8.1 Discharging direction after bend

9 Running direction of the clothing

9.1 Transverse direction

10 Sliding shoe

11 Grooves

12 Cleaning opening

12.1 Slanted periphery

13 Cleaning zone

14 Nozzle block

15 Propulsion jet nozzle

16 Supply line

A Angle

B Angle

1-16. (canceled)
 17. A device for cleaning a clothing having acontinuously revolving running direction along a clothing plane in amachine for at least one of producing or processing a paper, cardboard,tissue web or other fibrous web, the device comprising: at least onecleaning nozzle for generating at least one cleaning jet from a fluid,said at least one cleaning jet being directed onto the clothing andimpacting the clothing in a region of a cleaning zone; said at least onecleaning nozzle providing said at least one cleaning jet with a velocitycomponent in a direction transverse to the running direction of theclothing; said at least one cleaning nozzle causing said at least onecleaning jet to impact the clothing at an angular range of 20°<B<80°relative to the clothing plane along the running direction of theclothing; a discharge duct for discharging the fluid and dirt releasedfrom the clothing by said at least one cleaning jet in a dischargingdirection; said discharge duct having a beginning and a first portionwith a receptacle opening at said beginning of said discharge duct, saidreceptacle opening pointing counter to the running direction of therevolving clothing; and said first portion of said discharge duct havinga cleaning opening pointing toward the revolving clothing and formingsaid cleaning zone.
 18. The device according to claim 17, wherein saidangular range is 30°<B<70°.
 19. The device according to claim 17,wherein said at least one cleaning nozzle causes said at least onecleaning jet to impact the clothing at an angular range of 45°<A<45°relative to the transverse direction.
 20. The device according to claim17, which further comprises a sliding shoe surrounding said cleaningopening and being associated with said first portion of said dischargeduct in a vicinity of said cleaning opening.
 21. The device according toclaim 20, wherein said sliding shoe slides on the clothing.
 22. Thedevice according to claim 17, wherein said first portion of saiddischarge duct has a flow cross section increasing, decreasing, or beingconsistent in said discharging direction.
 23. The device according toclaim 17, wherein at least said first portion of said discharge duct hasa flow cross section with exclusively rounded corners.
 24. The deviceaccording to claim 17, wherein at least said first portion of saiddischarge duct has a flow cross section being tubular or made from atube.
 25. The device according to claim 17, wherein said first portionof said discharge duct has a centerline, and said cleaning opening has aface being inclined relative to said centerline in said dischargingdirection.
 26. The device according to claim 25, wherein said firstportion of said discharge duct is tubular, and said face of saidcleaning opening diverges from said centerline.
 27. The device accordingto claim 17, wherein said cleaning opening has a shape tapering orsteadily tapering or tapering corresponding to a parabolic shape in saiddischarging direction.
 28. The device according to claim 17, whereinsaid first portion of said discharge duct has a lateral wall, and saidat least one cleaning nozzle is disposed in said lateral wall.
 29. Thedevice according to claim 20, wherein said at least one cleaning nozzleis disposed in said sliding shoe in a vicinity of said first portion ofsaid discharge duct.
 30. The device according to claim 26, wherein saidat least one cleaning nozzle causes said at least one cleaning jet toimpact a peripheral region adjacent said cleaning zone.
 31. The deviceaccording to claim 17, wherein said at least one cleaning nozzleincludes at least two mutually opposite cleaning nozzles.
 32. The deviceaccording to claim 31, wherein said at least two mutually oppositecleaning nozzles are offset in the running direction of the clothing.33. The device according to claim 17, wherein said receptacle openinghas a face, and said first portion of said discharge duct has anaperture for delimiting said face of said receptacle opening.
 34. Thedevice according to claim 33, wherein said aperture is adjustable. 35.The device according to claim 17, wherein said discharge duct has afurther portion downstream of said first portion of said discharge duct,said further portion has a bend, and said discharging direction isdirected away from the clothing downstream of said bend.
 36. The deviceaccording to claim 35, which further comprises propulsion jet nozzlesdisposed in a vicinity of said bend of said further portion, saidpropulsion jet nozzles acting in said discharging direction downstreamof said bend.
 37. A method for cleaning a clothing continuouslyrevolving in a running direction along a clothing plane in a machine forat least one of producing or processing a paper, cardboard, tissue webor other fibrous web, the method comprising the following steps:providing a discharge duct having a first portion; forming a cleaningopening within the first portion of the discharge duct, the cleaningopening pointing toward the revolving clothing and forming a cleaningzone; forming a receptacle opening in the first portion of the dischargeduct and orienting the receptacle opening counter to the runningdirection of the revolving clothing; using at least one cleaning nozzleto generate at least one cleaning jet from a fluid; orienting the atleast one cleaning jet toward the cleaning zone; directing the at leastone cleaning jet onto the clothing to impact the clothing at an angularrange of 20°<B<80° relative to the clothing plane in the runningdirection of the clothing; and using the cleaning jet to discharge thefluid and dirt being released from the clothing in a dischargingdirection.